In the 2011 NEC article 110.24 has a few changes that need to be be addressed. Under 110.24(A) Field Marking, service equipment in other than a dwelling unit shall be field marked with the maximum available fault current. This is something you will have to get with the utility or the engineer for the project to be able to calculate. The field markings will have to be able to with stand the elements when a attached to a disconnect or panelboard out in the field. Section 110.24(B) Modifications will make you as the installer responsible to attach newly calculated fault current information to the equipment based on modification made to the circuits. All information provided will have to with stand the elements in which they are installed so a Sharpie or Magic Marker is not going to meet the requirements of this new change because they don’t last out in the weather. Till next time work safe…
